This invention relates to a horizontal mold clamping and vertical injection type die cast machine, and more particularly to an injection device supporting structure for supporting the injection device by a stationary platen.
Injection molding machines such as a die cast machine and a plastic injection molding machine are generally termed an injection die cast machine in the following since these machines are similar, and the term "material to be injected" means molten metal in the case of a die cast machine whereas plastic resin in the case of an injection molding machine.
In the prior art die cast machine and plastic injection molding machine, the mold clamping direction and the injection direction are generally the same, but in recent years, a horizontal mold clamping and vertical injection type die cast machine has been developed. Examples of such types of die casting machines are disclosed in Japanese Patent Publication Nos. 55859/1983 (now Japanese Patent No. 1222503) and 13941/1984 (now Japanese Patent No. 1237694).
As will be described later, with these prior art machines, after pouring molten metal into a casting sleeve, the sleeve is raised to abut against a stationary sleeve and the molten metal is injected into a mold cavity by an oil pressure operated plunger.
These prior art horizontal mold clamping and vertical injection type die casting or injection molding machines are advantageous in that the length of the molten metal in the injection sleeve is short so that the temperature lowering is small, that the contact area between the molten metal and air is small so that the number of voids formed in the product caused by gas contained in the injection cylinder is small, and that at the time of completing the filling, the injection pressure is efficiently transmitted since the injection plunger is correctly opposed to the mold cavity. But there are problems in the supporting structure of the injection device.
More particularly, in the prior art injection molding machine, since the injection device is supported by tie bars depending from columns supporting a stationary molding die plate, the columns tend to bend due to the weight of the injection device, so that a gap is formed between the injection sleeve and the sleeve of the metal mold. Consequently, a substantial number of the products would become rejects or molten metal would leak through the gap. Moreover, as the tie bars require a large space, the width of the die cast machine increases.